/*px em rem 等长度单位演示*/
html{
    font-size: 62.5%;/*16px*0.625=10px*/
}
body{
    font-size: 1em;
}
.value_px{
    font-size: 32px;
}
.value_em{
    font-size: 2em;
}
.value_rem{
    font-size: 2rem;
}
/* 颜色值 */
.color_name{
    color: tomato;
}
.color_hex{
    color: #00ff00;
}
.color_fun{
    color: rgb(0,0,255);
}
/* 图片函数 url */
.img_url{
    width: 1080px;
    height: 697px;
    background-image: url(qq_touxiang.jpg);
    font-weight: bolder;
}
/* 常见字体样式属性 */
.font_demo{
    /* font: 400; */
    color: rosybrown;
    /* 字体种类 */
    font-family: 宋体, sans-serif;
    /* 字体大小 */
    font-size: 2em;
    /* 字体样式 */
    font-style: italic;
    /* 字体粗细 */
    font-weight: 400;
}
.text_demo{
    color: springgreen;
    font-size: 2em;
    border:1px solid red;
    width: 50rem;
    height: 10rem;
    /* 对齐方式 */
    text-align: left;
    /* 行高 */
    line-height: 10rem;
    text-decoration: underline;
    text-indent: 3rem;
    letter-spacing: 1rem;
    word-spacing: 2rem;
}
/* 列表样式 */
ul{
    font-size: 2em;

}
.list_demo1{
    list-style: circle inside;
}
.list_demo2{
    list-style: none;
}
.list_demo3{
    list-style-image: url(logo1.gif);
    list-style-type: none;
    list-style-position: inside;
}
.list_demo4{
    list-style: none url(logo1.gif) inside;
}
.bg_box{
    border: 1px solid springgreen;
    width: 40rem;
    height: 10rem;
}
.bg_demo1{
    background-color: aqua;
}
.bg_demo2{
    background-image: url(logo1.gif);
}
.bg_demo3{
    background-image: url(logo1.gif);
    /* background-repeat: no-repeat; */
    background-repeat: repeat-x;
}
.bg_demo4{
    background-image: url(logo1.gif);
    background-repeat: no-repeat;
    background-position: center center; 

}
.bg_demo5{
    background-image: url(logo1.gif);
    background-repeat: no-repeat;
    background-position: top right; 
    background-attachment: fixed;
}
.bg_demo6{
    background: cornsilk url(logo1.gif) repeat-y top right fixed;
}
/* 表格样式 */
.table_demo{
    font-size: 2rem;
    border: 1px solid #000000;
    width: 70%;
    margin: 0 auto;
    table-layout: fixed;
    border-collapse: collapse;
    /* border-collapse: separate; */
    border-spacing: 10px;
    empty-cells: show;
}
.table_demo caption{
    font-size: 2.5rem;
}
.table_demo th, .table_demo td{
    border-top: 1px solid #000000;
    border-bottom: 1px solid #000000;
    text-align: center;
}
.table_demo thead{
    background-color: brown;
    color: chartreuse;
}
.table_demo tbody tr:hover{
    background: chartreuse;
    cursor: pointer;
}
.table_demo tfoot td{
    text-align: right;
    padding-right: 2rem;
}

/* 表单样式 */
.form_demo{
    margin: 0 auto;
    font-size: 1.4rem;
    border: 1px solid springgreen;
    background: white;
    width: 35rem;
    height: 15rem;
    text-align: center;
}
.form_demo input[type="text"],.form_demo input[type="password"]{
    border-left:0 ;
    border-right: 0 ;
    border-top: 0;
    border-bottom: 1px solid #000000;
    width: 200px;
    height: 37px;
    padding-left: 42px;
}
.form_demo #username{
    background: white url(username.png) no-repeat top left;
}
.form_demo #pwd{
    background: white url(pwd.png) no-repeat top left;
}
.form_demo [type="submit"]{
    width: 100px;
    height: 37px;
    background-color:rgb(0, 162, 255) ;
    border: 1px dashed #00ff00;
    border-radius: 10px;
    color: chartreuse;
}